1. Field of the Invention
The present invention generally relates to an air spray gun that atomizes a paint or the like under the action of pressurized air and sprays the resultant paint mist to an object which is to be coated with the paint, and more particularly, to an attachment which is to be connected to an air inlet of the air spray gun to adjust and check the pressure of air introduced through the air inlet into the spray gun.
2. Description of the Related Art
The air spray gun is used to atomize a paint under the action of pressurized air and spray the paint mist produced as above. Therefore, the quality of a paint coating thus formed depends upon the condition of such pressurized air. Normally, the worker using the spray gun checks the air pressure at the time of spraying a paint. In case it is necessary to change the spraying conditions correspondingly to a surface variation of an object to be coated and use of another paint, the worker has to adjust pressurized air for supply to the air spray gun by operating a pressure reducing valve or the like provided in the middle of a supply passage from an air source until an air pressure required for the spraying is attained. Also, for continuously assuring a stable quality of the coating, it is necessary to keep a constant air pressure and check the air pressure during spraying as well.
Normally, the air spray gun is supplied with pressurized air whose pressure has been adjusted at an air compressor or the like located away from the spray gun. Therefore, many of the air spray guns have no air pressure control provided on themselves. When changing the air pressure or adjusting it to a correct level, the worker has to leave the working site and go to the air compressor located away from the site to adjust a regulating valve of the compressor. Thus, the worker has to interrupt the coating work at each time of the adjustment. To solve the above problem, there have been proposed some air spray guns provided with a valve to adjust the air flow rate instead of adjusting the spraying pressure. With such a valve, the worker can adjust the spraying pressure but cannot still check the spraying pressure. In effect, the worker has to address the air pressure adjustment intuitively by experience.
Improvement in appearance, by the finish coating, of products of commerce is very important for raising the added value of the products as well as for economic use of an expensive paint having been used to meet the recent need for a higher quality. One of the basic coating techniques for the quality coating is to assure a correct spraying pressure. To solve the scattering of paint mist as a basic problem of the air spray gun, it has been required to improve the efficiency of paint adhesion for higher friendliness to the worker and environment. One of the possible solutions is to reduce the spraying pressure. The reduced spraying pressure has been proved to be practically effective for less scatting of the paint mist. The reduction of air pressure is legally required in some cases in which it will be required that the spraying pressure can be checked.
A spray gun incorporating a pressure gauge will be a solution to the above problem, but it will be expensive. Generally, however, a joint having a pressure gauge is connected to the air inlet of the spray gun when it is necessary to check the spraying pressure.